A conventional piezoelectric oscillator has been formed by use of a fastening method by adhesive agent 101 or a fastening method by solder having the ratio of Sn to Pb, 6:4 or 9:1, for fastening a piece of piezoelectric oscillator. Further, a pressure seal method has been employed in which the case is coated with solder 102 or gold by plating, and a welding method such as a cold pressure welding method are employed for sealing.
Furthermore, a conventional resin mold piezoelectric oscillator is constructed as depicted in FIG. 16. This piezoelectric oscillator is an integrally formed oscillator in which a piece of piezoelectirc oscillator 103 is adhered to inner lead 105 of stem 104 by an adhesive agent such as polyimide series one, stem 104 and case 106 are sealed by gold as shielding material 107 and the pressure seal type piezoelectric oscillator and the lead frame are adhered by welding.
A conventional piezoelectric oscillator has been constructed as depicted in FIG. 17, wherein the above-described pressure seal type piezoelectric oscillator 109, semiconductor 110 which electrically oscillates pressure seal type piezoelectric oscillator 109 and the lead frame which electrically connects pressure seal type piezoelectric oscillator 109 with semiconductor 110 have been molded by resin 111.
However, when the above-described prior art is employed as SMT (Surface Mount Technology) parts, the temperature of the parts rises up to 220.degree.-260.degree. C. when they are packaged on the substrate and the solder containing 40% and less of lead are melted. In addition to this fundamental disadvantage, deterioration of the properties, shift in frequency and in equivalent resistance value of pressure seal type piezoelectric oscillator by gas containing organic components ejected from the soldering are caused.
It is, therefore, an object of the invention to solve the above-described disadvantages and to provide an improved pressure seal type piezoelectric oscillator, resin mold type piezoelectirc oscillator and piezoelectric oscillating apparatus, each having heat resistance applicable for SMT packaging at 260.degree. C. and higher and having excellent properties with respect to high temperature frequency aging.